Optical coherence tomography (OCT) detects tissue interfaces based on their differential reflection of light. These techniques are non-invasive and employ wavelengths of light that have considerable depth of penetration in tissue but no known detrimental biological effects. Studies described in this proposal will determine if this technology can be used as a new imaging tool for periodontal diagnosis. We will adapt existing laser equipment, available through out collaboration at Lawrence Livermore Laboratories, to test this hypothesis. Our preliminary data demonstrated that sufficient light penetrates gingival tissue to record a meaningful optical signal. Furthermore, in ophthalmologic applications, OCT provides higher resolution than traditional diagnostic techniques. Optical imaging will have many advantages over existing periodontal diagnostic procedures. OCT will produce two- or three-dimensional images depicting the topology of the pocket and connective tissue attachment and can be used to assess relationships between hard and soft tissue. These visual records can be filed as a part of the patient record. Errors associated with examiner variability in pocket probing measurements will be eliminated. Furcation involvement associated with early loss of attachment can be detected, rapidly recorded and compared with subsequent readings following therapy. Fenestrations and dehiscences, often not diagnosed until surgery, can also be detected. Patient acceptance of this technique will be far greater than for most dental procedures. OCT is entirely non-invasive and can be performed repeatedly to monitor progress of therapy without any danger to the patient. Oct is painless, rapid, and can be easily incorporated into a routine dental examination. This technology will also be a powerful research tool. Oct can potentially be used to differentiate between active and inactive periodontal disease. The orientation of collagen fibers before, during and following therapy can be repeatedly assessed to evaluate the progress of periodontal treatment. Moreover these optical techniques can spectroscopically detect, quantify and monitor small concentrations of specific molecules. This potential application will permit rapid, non- invasive measurement of multiple molecules within periodontal pockets. The Specific Aims of this proposal are to: 1. Adapt existing laser equipment and technology to demonstrate that OCT can be used for periodontal diagnoses. 2. Compare diagnostic findings derived from OCT to measurements obtained with histometric methods. 3. Construct a prototype clinical periodontal OCT imaging system at a cost that is affordable for clinical dental practices.